I sync my ~/Documents folder with u1 cloud. Once I modify any file in this folder, instead of a new version there is an empty file with the same name as document upload on the server.

And next time I log in, U1 tries to sync this empty file back to my ~/Documents folder. As the result, I have an empty "name.odt" file and renamed to "name.odt.u1conflict" real document. Problem appears after I update to the 11.04.